Composition comprised of a water-in-soluble n-methylol-amide-acrylic acid ester copolymer with a polyalkylene glycol

ABSTRACT

FIBERS IN NON-WOVEN FIBROUS PRODUCTS ARE BONDED TOGETHER BY A BINDER COMPRISING THE HEAT-CURED PRODUCT OF A WATER INSOLUBLE COPOLYMER OF (I) AN N-METHYLOLAMIDE WHICH IS N-METHYLOLACRYLAMIDE OR N-METHYLOLMETHACRYLAMIDE, AND (II) AN ACRYLIC ACID ESTER OF ACRYLIC ACID OR METHACRYLIC ACID AND A C1 TO C8 ALKANOL, MODIFIED WITH (III) A POLYALKYLENE GLYCOL OF THE FORMULA   HO-(RO)N-H   WHEREIN R IS AN ALKYLENE GROUP OF 2 TO 6 CARBON ATOMS AND N IS A NUMBER HAVING AN AVERAGE VALUE OF 4 TO 50. PREFERRED ACRYLIC ACID ESTERS ARE ETHYL ACRYLATE AND BUTYL ACRYLATE, AND THE PREFERRED POLYALKYLENE GLYCOL IS A POLYETHYLENE GLYCOL CHARACTERIZED BY A MOLECULAR WEIGHT IN THE RANGE OF 300 TO 2000. THE COPOLYMER MAY ALSO CONTAIN UNITS DERIVED FROM UNSATURATED ALIPHATIC CARBOXYLIC ACIDS. PREFERABLY THE COPOLYMER CONTAINS UNITS DERIVED FROM ITACONIC ACID. THE ITACONIC ACID STABILIZES AQUEOUS DISPERSIONS OF THE COPOLYMER AND ADDS STIFFNESS TO THE TREATED FIBEROUS PRODUCTS WITHOUT DETRACTING FROM RESILIENCE AND SOLVENT RESISTANCE.

Int. Cl. C08f 29/50, 45/26 U.S. Cl. 26029.4 UA 9 Claims ABSTRACT OF THEDISCLOSURE Fibers in non-woven fibrous products are bonded together by abinder comprising the heat-cured product of a water insoluble copolymerof (i) an N-methylolamide which is N-methylolacrylamide orN-methylolmethacrylamide, and (ii) an acrylic acid ester of acrylic acidor methacrylic acid and a C to C alkanol, modified with (iii) apolyalkylene glycol of the formula wherein R is an alkylene group of 2to 6 carbon atoms and n is a number having an average value of 4 to 50.Preferred acrylic acid esters are ethyl acrylate and butyl acrylate, andthe preferred polyalkylene glycol is a polyethylene glycol characterizedby a molecular weight in the range of 300 to 2000. The copolymer mayalso contain units derived from unsaturated aliphatic carboxylic acids.Preferably the copolymer contains units derived from itaconic acid. Theitaconic acid stabilizes aqueous dispersions of the copolymer and addsstiffness to the treated fibrous products without detracting fromresilience and solvent resistance.

This application is a continuation of my copending U.S. patentapplications Ser. No. 36,499, filed May 11, 1970 now abandoned, and Ser.No. 182,877, filed Sept. 22, 1971.

The present invention relates to processes for bonding fibers ofnon-woven fabrics. The non-woven fabrics are fibrous or filamentousproducts having a carded fiber structure or comprising fibrous mats inwhich the fibers or filaments are distributed haphazardly or in randomarry. The expression random array is intended herein to include thearray of fibers in a carded web wherein partial orientation isfrequently present as well as other arrays in which the fibers are in acompletely haphazard distributional relationship.

The bonded non-woven fibrous products of this invention are useful inthe production of articles of either fiat or three-dimensional shape,including insulating material and the like. Particularly the bondedfibrous products are used as textile products in articles of dress, forexample, as interliners for the collars and cuffs of shirts, especiallythe relatively open-weave type used for summer wear.

Bonded fibrous products suitable for such uses must be resilient withcrush resistance and shape retention; they must have a soft, but firm,feel or hand; and they must be of sufiicient solvent resistance towithstand drycleaning operations. Upon drycleaning, some products of thetype heretofore produced lose their soft hand and draping qualities andmay show discoloration (yellowing) and loss of strength upon ageing.

The compositions used for bonding non-woven fabrics in accordance withthe present invention comprise the heat-cured product of a mixture of acopolymer of an N-methylolamide and acrylic acid ester and a polyalk'yl-United States Patent p we ene glycol. The reresulting non-woven fabricshave excellent resilience, are of a soft, but firm hand and exhibitexcellent solvent-resistant properties. In its broadest description, thepresent invention is a non-woven fibrous product resistant todrycleaning and laundering, the fibers in the product being bondedtogether by a binder comprising a heat-cured product of a mixture of (1)a waterinsoluble copolymer of (i) an N-methylolamide which isN-methylolacrylamide or N-methylolmethacrylamide, and (ii) an acrylicacid ester of acrylic acid or methacrylic acid and a (C to C alkanol,and (2) a polyalkylene glycol of the formula wherein R is an alkylenegroup of 2 to 6 carbon atoms and n is a number having an average valueof 4 to 50. The copolymer may contain units derived from an unsaturated(C to C aliphatic carboxylic acid. Preferably the copolymer containsunits derived from itaconic acid. The process of the present inventionis a process of making'a non-Woven fabric which comprises associating inrandom array, within a web or mat, a mass of fibers, bringing intocontact with the fibers a binder comprising an aqueous dispersioncontaining dispersed therein a water-insoluble copolymer and glycoldescribed above, drying the resulting fibrous mass to effect fusion ofthe polymer and bonding of the fibers, and then curing the fabric byheating the fibrous product at a temperature of 210 F. to 750 F. toproduce a soft, resilient nonwoven fibrous product of excellentsolvent-resistant properties.

Kine et al., U.S. Pat. 3,157,562, issued Nov. 17, 1964, disclosesnon-woven fibrous products bonded by the heatcured product of awater-insoluble linear copolymer of an N-methylolamide, an amidegroup-containing monomer, and an acrylic acid ester, among others.Specifically disclosed N -methylolamides include N methylolacrylamideand N-methylolmethacrylamide; specifically disclosed amidegroup-containing monomers include acrylamide and methacrylamide andspecifically disclosed esters include ethyl acrylate and butyl acrylate.All of the disclosed compositions contain the amide groupcontainingcomponent and none of the compositions con tains a polyalkylene glycolcomponent.

British patent specification 1,100,240 relates to a process for bondingfleeces with an aqueous dispersion which contains (a) a polymer orcopolymer prepared from a vinyl or divinyl monomer and containing groupscapable of reacting with isocyanate groups and (b) an isocyanategroup-containing reaction product of a compound carrying at least 2hydroxyl groups and a stoichiometric excess of a polyisocyanate. Forexample, the British patent teaches bonding compositions which areaqueous dispersions of butadiene-butyl acrylate-isocyanate/polyethyleneglycol copolymers.

In accordance with the present invention, it has been found thatparticular copolymers of N-methylolamides and acrylic acid estersadmixed with polyalkylene glycols when applied to non-woven fabrics andcured by heating at elevated temperatures, impart resilience, soft hand,resistance to laundering operations such as may be performed with moderndetergents, as well as resistance to drycleaning by chlorinatedhydrocarbons, such as carbon tetrachloride. The compositions of thepresent invention comprise water-insoluble copolymers obtained byemulsion copolymerization of a mixture of copolymerizablemonoethylenically unsaturated molecules comprising (i) 1 to 8% by weightof N-methylolacrylamide or N- methylolrnethacrylamide and (ii) 92 to 99%by weight of an acrylic acid ester of acrylic acid or methacrylic acid 3and a (C to C alkanol, admixed with (iii) 0.5 to 10.0% by weight of apolyalkylene glycol of the formula wherein R is an alkylene group of 2to 6 carbon atoms atoms and n is a number having an average value of 4to 50. Preferably, the compositions comprise copolymers of 3 to 4.5weight percent of the N-methylolamide and 95.5 to 97 weight percent ofacrylic acid ester modified by admixture with 2 to 5 weight percentpolyalkylene glycol. These weight percents are optimum amounts andresult in compositions which impart the most desired properties tonon-woven fibrous products. The components however may be used inpercentages outside of the ranges given.

As pointed out above, the mixture of copolymerizable monoethylenicallyunsaturated molecules may include an unsaturated (C to C aliphaticcarboxylic acid. Preferably the unsaturated aliphatic carboxylic acid isitaconic acid. The unsaturated aliphatic carboxylic acid, particularlyitaconic acid, stabilizes aqueous dispersions of the copolymer and addsstiffness to the treated fibrous products without detracting fromresilience and solventresistance. The acid is preferably present inquantities by weight of 0.5 to 5.0% based on the total weight of thecopolymer. Examples of suitable acids other than itaconic acid includeacrylic acid, methacrylic acid, citraconic acid, etc.

Examples of the acrylic acid esters (ii) include methyl methacrylate,ethyl methacrylate, propyl methacrylate, butyl methacrylate, octylmethacrylate, octadecyl methacrylate, methyl acrylate, ethyl acrylate,butyl acrylate, octyl acrylate and octadecyl acrylate.

Fabric webs bonded with the ethyl acrylate-containing copolymers of thepresent invention exhibit excellent resilience and solvent-resistance.Fibrous products bonded with the butyl acrylate-containing copolymers ofthe present invention show excellent resilience but somewhat lesssolvent-resistance than the ethyl acrylate copolymer bonded webs. Forthis reason the ethyl acrylate copolymers are a preferred embodiment ofthe present invention. However, even better results are obtainable whenboth ethyl acrylate and butyl acrylate are in the copolymer. An exampleof this is a copolymer of 48% by weight of butyl acrylate, 48% of ethylacrylate, about 0.5 to 2% of itaconic acid, and about 2 to 3.5% byweight of a mixture of approximately equimolar amounts of acrylamide andN-methylolacrylamide.

Examples of suitable polyalkylene glycols include polyethylene glycols,polypropylene glycols, polybutylene glycols and polyhexylene glycols.Polyalkylene glycols with a molecular weight 194 to 4000 are suitable inthe present invention while polyalkylene glycols with a molecular weightin the range of 300 to 2000 are preferred. Polyethylene glycols withinthese molecular weight ranges are the most preferred polyalkyleneglycols.

It should be noted that the copolymer in the aqueous dispersion of thepresent invention must be obtained by emulsion copolymerization of amixture of the copolymerizable molecules described above forsatisfactory results. Omission of any one of the groups ofcopolymerizable molecules or substitution for any one of the groups willproduce a copolymer which is not completely satisfactory as thecopolymers of the present invention for bonding non-woven fibers. It hassurprisingly been found that omission of the polyalkylene glycolmodifier results in bonding compositions which produce non-woven fibrousproducts characterized by poor resilience, stiffness and solventresistance. It appears that in the absence of the polyalkylene glycolmodifier, the N-mcthlolamideacrylic acid ester copolymer migrates towardthe surface of the fabric after removal from the padding bath orapplication dispersion thereby resulting in non-uniform application ofthe binder to the fibrous webs. The present invention therefore residesin the cooperative and interdependent manner in which the components arecombined .4 to produce bonding compositions which impart resilience andsolvent-resistance to fibrous products.

The copolymers of the present invention may be produced by conventionalemulsion polymerization procedures employing a suitable emulsifier ormixtures of a non-ionic with a cationic or an anionic emulsifier inconjunction with a free-radical initiator which may be a component ofany of the well-known redox systems. 'Examples of emulsifiers that maybe used include sodium lauryl sulfate, t-octylphenoxypolyethoxyethanolscontaining about 10 to 50 oxyethylene units per molecule and laurylpyridinium chloride. The amount of emulsifier may range from about 0.5to 7.5% on the weight of monomers. Any free-radical initiator such asazodiisobutyronitrile, tbutyl hydroperoxide, and ammonium or potassiumpersulfates may be employed. The initiator may 'be present in amountfrom 0.1 to 2.0% on the weight of monomers, the amount preferably beingsufiicient to provide molecular weights of about a million or higher inthe particles of the emulsion polymer produced.

The polymers used as binders of the present invention may also be graftor block copolymers wherein one or more, but not all, of the monomersare copolymerized within the first polymer obtained. Thus, the acrylicacid ester or the N-methylolamide may first be homopolymerized orcopolymerized with one or more, but less than all, of the comonomers tobe introduced into the ultimate copolymer, and then the last monomer ormonomers can be added to the system and copolymerized or grafted on tothe first homopolymer or copolymer formed. The same procedure may beused in reverse order to graft the acrylic acid ester or N-methylolamideon to a previously-formed homopolymer or copolymer of other monomericunits. Again, a plurality of monomeric units may be introduced insuccession and the acrylic acid ester or N-methylolamide may beintroduced at thebeginning, at any intermediate stage, or at the end asdesired.

The fibrous webs may be formed in any suitable manner such as bycarding, garnetting, or by dry deposition from an air suspension of thefibers. The thin web or fleece obtained from a single card may betreated in accordance with the present invention, but generally it isnecessary and desirable to superpose a plurality of such webs to buildup the mat to sufficient thickness for the end use intended,particularly in the making of heat insulation. In building up such amat, alternate layers of carded webs may be disposed with their fiberorientation directions disposed at 60 or angles with respect tointervening layers.

The fibers from which the webs may be made include cellulosic fiberssuch as cotton, rayon, jute, ramie, and linen; also cellulose esterssuch as cellulose aceate; silk, wool, casein, and other proteinaceousfibers; polyesters such as poly(ethylene glycol terephthalate);polyamides such as nylon; vinyl resin fibers such as the copolymer ofvinyl chloride and vinyl acetate, polymers of acrylonitrile containing70% to by weight of acrylonitrile including those available under thetrademarks Orlon and Acrilan; and siliceous fibers such as glass andmineral wools.

The aqueous dispersion of the water-insoluble copolymer of the presentinvention may be applied to the web or mat of fibers in any suitablefashion such as by spraying, dipping, roll-transfer, or the like. Theconcentration may be from 5% to 60% by weight, and preferably from 5% to25%, at the time of application as an aqueous dispersion.

The binder dispersion may be applied to the dry fibers after theformation or deposition of the web or mat so as to penetrate partiallyinto or completely through the interior of the fibrous products.Alternatively, the binder dispersion may be applied to the fibers asthey fall through the settling chamber to their point of deposition.This is advantageously accomplished by spraying the binder dispersioninto the settling chamber at some intermediate point between the top andthe bottom thereof. By so spraying the fibers as they descend to thepoint of collection, it is possible to effect a thorough distribution ofthe binder among the fibers before they are collected into the product.In the production of certain fibrous products wherein a hot molten massof a polymer, such as nylon or a fused siliceous mass or glass, isdisrupted by jets of heated air or steam, the binder dispersion may besprayed directly on the fibers while still hot and very shortly beforetheir deposition so that quickly after deposition the binder is set tobond the fibers in proper relationship. Preferably, however, applicationof the binder dispersion to the fibrous prouct is made at roomtemperature to facilitate cleaning of the apparatus associated with theapplication of the binder dispersion. The binder dispersion may beapplied to one or both surfaces of the fibrous product or it may bedistributed through the interior as well.

The binder of the present invention may be applied in conjunction withother binders, such a glue. Similarly, the use of potentially adhesivefibers within the fibrous product may also be resorted to in conjunctionwith the use of of a binder of the present invention.

If desired, the aqueous dispersion of the polymer and condensate mayalso contain a wetting agent to assist penetration of the fibrous web ormat to which it is applied, and it may contain either a foaming agent toprovide the binder in a foamed condition in the final product or it maycontain a defoamer when the ingredients of the aqueous dispersions havea tendency to give rise to foaming and in a particular case such foamingis undesirable. The conventional wetting agents, such as the sodium saltof dioctylsulfosuccinic acid may be used and the conventional foamingand defoaming agents may be employed, such as sodium soaps, includingsodium oleate for foaming and octyl alcohol or certain silicones fordefoaming.

An acid catalyst may be included in the aqueous dispersion at the timeit is applied to the fibrous web or it may be applied to the fibrous Webbefore or after the copolymer is applied. Examples of acidic catalyststhat may be employed include oxalic acid, dichloracetic acid,ptoluenesulfonic acid, and acidic salts such as ammonium sulfate andamine salts, such as the hydrochloride of 2- methyl-Z-aminopropanol-l.

The proportion of the polymer that is applied to the web or mat is suchas to provide 15 to 50% (or, in some cases, even up to 75%) by weight ofcopolymer based on the total weight of copolymer and fibers. Afterapplication of the aqueous dispersion of the water-insoluble copolymerto the fibrous web, the impregnated or saturated web is dried either atroom temperature or at elevated temperatures. The web is subjected,either after completion of the drying or as the final portion of thedrying stage itself, to a baking or curing operation which may beeffected at a temperature of about 210 to about 750 F. for a periodwhich may range from about one-half hour at the lower temperatures to aslow as five seconds at the upper temperatures. The conditions of bakingand curing are controlled so that no appreciable deterioration ordegradation of the fibers or copolymer occurs. Preferably, the curing iseffected at a temperature of 250 to 325 F. for a period of 2 to minutes.

It is believed that the curing operation in some way causes reaction ofthe polymer molecules to effect crosslinking thereof to a condition inwhich the binder is highly resistant to laundering and drycleaning. Thisreaction involves the N-methylol groups of some polymer molecules withthe reactive hydrogen-containing groups of others of the polymermolecules. It is also believed that the curing causes some reactionbetween the N-methylol groups of the polymer molecules and reactivegroups in the fibers such as the hydroxyl groups of the cellulosefibers. Also, presence of the polyalkylene glycol in binder of thepresent invention appears to reduce or prevent migration of emulsionpolymer particles resulting in greatly improved uniformity ofdistribution of binder in the bonded web. Consequently resilience andsolvent-resistant properties are not adversely affected by irregularityof distribution of the binder.

The bonded fibrous products of the prment invention are characterized byresilience, softness, flexibility, resistance to discoloration,resistance to chlorinated hydrocarbon dry-cleaning fluids, andresistance to laundering. Because of the softness and flexibility andgood draping qualities of the products of the present invention, theyare particularly well-adapted for use in garments where porosity,especially to moisture vapor, and soft hand and feel, make the productsadvantageous where contact with the skin of a wearer may be involved. Ingeneral, the products are quite stable dimensionally and have goodresilience and shape-retention properties. They are adapted for use notonly in garments but as padding or cushioning, and in moisture-absorbingarticles, such as bibs and diapers. They are also useful as heatandsound-insulating materials and as filtration media, both for liquids andgases. They can be laminated with paper, textile fabrics, or leather tomodify one or both surfaces of the latter materials. They may be adheredto films of cellophane, polyethylene, saran, polyethylene glycolterephthalate (Mylar) or metallic foils, such as of aluminum, to improvethe tear strength of such films and foils, to make the latter moreamenable to stitching, and to modify other characteristics includingstrength, toughness, stiffness, appearance, and handle.

As stated hereinabove, the products obtained from nonwoven fibrous websemploying the aqueous dispersion of the composition of the presentinvention impart good resistance to laundering and drycleaning whenapplied as the sole binder and cured in the manner stated hereinabove.Such products are also free of any tendency to become discolored onchlorination and ironing. However, for some purposes, particularly wherechlorination and/ or ironing are not encountered, the composition of thepresent invention may be employed in conjunction with a thermosettingresin condensate, such as an aminoplast or polyepoxide. The amount ofsuch condensate that may be included in the binder compositions may beas high as 20% by weight of the copolymer, a proportion of 3% to 10%being preferred when such condensate is used.

The aminoplast condensates which may be employed are the low molecularweight or monomeric reaction products of formaldehyde with urea,thiourea, biuret, or other homologs or derivatives thereof, such asN,N-ethyleneurea, N,N'-dimethylurea, N,N'-diethyl-urea,N,N-dimethoxymethylurea, N,N-dimethoxymethylurea,N,N'-diethoxyethylurea, tetramethoxymethylurea, andtetraethoxyethylurea. Similar reaction products of formaldehyde withtriazines, such as mela-mine may also be employed, such asN,N-dimethylmelamine and alcohol-modified melamineformaldehydethermosetting resin condensates, e.g. of methyl and ethyl alcohols, forexample, dimethoxymethyl-monomethylolmelamine. Preferably, the extent ofcondensation of these resin-forming aminoplast condensates is such thatthey are still soluble in water or selfdispersible therein to acolloidal condition.

The epoxy thermosetting resin-forming condensates may be eitherether-soluble or self-dispersible in water. The water-soluble types maybe any of those having the Formulas III, IV, V, and VI:

o o (v) where m is an integer having a value of 2 to 4, and z is anumber having an average value of 1 to 5. i

The water-insoluble but self-dispersible condensates containing epoxidegroups include the compounds of Formula IV above wherein y has anaverage value of to and also compounds of Formula VI:

O 0 (VI) where is the p-phenylene group, and p is a number having anaverage value of 1 to 3.

While the binder may be preferentially applied, if desired, to portionsof the fibrous product, such as one or both of the faces thereof, it ischaracteristic of the binder of the present invention, if suchpreferential treatment is not desired, substantially uniformdistribution may be obtained because of the reduced tendency of thebinder after initial distribution throughout the body of the fibrousproduct to migrate to the surfaces thereof during drying. As pointed outabove, it is thought that this reduced tendency of the binder to migrateis due to the presence of the polyalkylene glycol component.

In the examples, parts and percentages are by weight unless otherwiseindicated.

EXAMPLE A Fibrous webs are formed by cross laying polyester fibers, 1.5denier and 1.5 inches in length. The webs, weighing from 1 ounce to 2ounces per square yard are placed between two screens of open mesh glasscloth and are dipped into shallow baths of an aqueous dispersioncontaining 10% by weight of an emulsion copolymer of 96.5 parts ethylacrylate and 3.5 parts N-methylolacrylamide and containing 4.3 percentof a sodium dodecyl benzene sulfonate emulsifier and prepared byemulsion copolymerization. The bath is prepared by admixing in anaqueous medium 143 parts of a 35% solids dispersion of the copolymer,1.5 parts of a mixture of 60% di-capryl sodium sulfosuccinate, 20%isopropanol and 20% Water, 5.0 parts ammonium nitrate and 347.0 partswater, and diluting to 10% solids. The supported webs are floated andallowed to wet thoroughly and are then submerged and rolled whilebeneath the surface of the bath to insure complete wetting and to insuredisplacement of air which may be trapped among the fibers. The wet webwhile still supported on the screens is passed between squeeze rolls toremove excess dispersion and is partially dried in infra-red heat to acondition where the wet fibrous web is strong enough to support itselfand can be removed from the glass screens. The web is dried incirculating air and cured for 5 minutes at 300 F. The webs are finallyconditioned for a minimum of 24 hours at 72 F and 65% relative humidity.

The resulting fabric web has weak areas and imperfections. Visualobservation of the padding operation on fabric Webs prepared as above,indicates that during the drying operation, the polymer dispersions tendto migrate to the surface of the webs causing non-uniform distributionand weak areas and imperfections in the final web. This observation isaffirmed by determining migration by staining the polyester fiber webswith Sevron Brilliant Red 4G, a dye which stains the polymer but not thepolyester fiber. The stained webs are then observed in a low power, 30magnifications microscope and the distribution of the polymer assessed.Poor polymer distribution, caused by poor migration control, isindicated by polymer concentration at the surfaces of the web while theinterioras seen on edges and out sectionsis starved of polymer.Additionally the webs show random areas of polymer concentration andother areas free of polymer. This example shows a fibrous product whichis not of the present invention. A comparison between this example andthe following examples illustrates the criticality of the polyalkyleneglycol component in the compositions of the present invention.

In this and the following examples, migration control is determined bythis preceding described method. Resilience where indicated in thefollowing examples also reflects distribution of the polymer since areaswhich have little or no binder are dead spots which do not recover.Resilience and stiffness are determined by the apparatus and process ofKelley, Alexander and Sioma described in their US. Pat. 3,620,071, Nov.16, 1971. Generally this process comprises subjecting the fabricspecimen to a longitudinal tensile load, twisting the specimen throughan angle of rotation by applying a releasable torque load around thelongitudinal axis of the specimen while retaining one end of thespecimen in a fixed position, and releasing the specimen from theapplied torque to cause the specimen to oscillate around its axis ofrotation and measuring the tensile load required and time for an initialcomplete oscillation at an applied tensile load at which A /A is between2.5 and 3.5, preferably 2.7, A and A being respectively the amplitude ofa first and second oscillation peak. In the examples of thisspecification, the load that causes oscillation at which A /A 2.7 isdetermined by increasing tensile loads in 5 gram increments up to 25 andin 25 gram increments thereabove. As per the Kelley, Alexander and Siomainvention the minimum tensile load required to give this oscillation andthe period of oscillation at this load are relatable to resilience andstiffness respectively of a fabric specimen. The resilience is inverselyproportional to the tensile load and the period is relatable tostiffness by the expression Stitfness= /P where P is the period requiredfor a complete oscillation in seconds. Resilience and stiffness may thengenerally be related to tensile load and period as follows:

TABLE 1 Resilience Tensile load, grams Resilience 1-30 Fast recovery.20-100 Medium recovery. Slow recovery.

Stiffness Tensile load range, grams 1/P Stiffness Examples B, C and 1 to4 In these examples, the procedure of Example A is repeated. In theseexamples, however, except for Example C, 2.5 parts of ethylene glycol orof an aqueous 25% solution of polyethylene glycol is added to the bathbefore impregnation of the web. In Example C, 6.2 parts of an aqueous10% polyethylene glycol solution is added. Properties of the resultingfibrous Webs are shown in Table 2.

Under the heading Resilience in this and the following tables, thenumerical value is the load in grams required to make [l /A 227 and thelower the value, the greater the resilience; the numerical values understiffness are those obtained by substituting the time in seconds of acomplete oscillation for P in the relationship 1/P the higher thevalues, the greater the stiffness; and the values given under theheading Solvent Resistance are the tensile strengths in oz./ in. widthof the fabric after soaking in perchloroethylene for 15 minutes, thehigher the value, the more solvent-resistant the fabric.-

Examples 1 through 4 illustrate compositions of the present invention. Acomparison of Examples A, B, C and 1 to 4 illustrate the critical natureof the polyalkylene glycol component of the present invention as it isdefined.

Examples 5 to 8 The procedure of Example 2 is repeated using varyingproportions of the polyethylene glycol of Example 2. The resultsobtained are shown in Table 3.

These examples illustrate compositions of the present invention usingvarious amounts of polyethylene glycol component.

Examples 9 to 12 In these examples fibrous webs are formed bycrosslaying polyester fibers, 1.5 denier and 1.5 inches in length. Thewebs are placed between two screens of open mesh glass cloth and aredipped into shallow baths of an aqueous dispersion containing by weightof an emulsion copolymer of a high molecular weight (about 1 million)haying various proportions of ethyl acrylate and N-methylolacrylamideand containing 4.3% of the sodium salt of dodecyl benzene sulfonate asan emulsifier. The baths are prepared by admixing in an aqueous medium143 parts of a 35% solids dispersion of the copolymer, 2.5 parts of a25% solids solution of a polyethylene glycol of 300 molecular weight,1.5 parts of a mixture of 60% di-capryl sodium sulfosuccinate, 20%isopropanol and 20% water, 0.5 parts ammonium nitrate and 347.0 partsWater, and diluting to 10% solids. The webs are padded, cured andconditioned per the procedure of Example A. Properties of the fabricwebs produced are given in Table 4.

These examples indicate compositions of the present invention containingvarious proportions of the N-methylolamide component.

Example 13 to 15 The procedure of Example 1 is repeated using webs ofrayon fibers, nylon fibers and webs of a blend of 1 part viscose rayon,1 part acetate and 1 part nylon. Results similar to those of Example 1are obtained.

1 Examples 16 and 17 The one-million molecular weight ethyl acrylatepolymers demonstrated in Examples 9 to 12 impart a high degree ofsolvent resistance with adequate resilience as indicated in Table 4. Apolymer of composition similar to those of Examples 9 to 12 and producedby a procedure analogous to that of those preceding examples but alteredto produce a polymer of lower molecular weight is compared to a polymerof higher molecular weight in Table 5.

TABLE 5 Amount of methylol MW of Properties of bonded fabric acrylamide,ethylpercent based acrylate Resili- Stifi- Solvent Example on polymerpolymer enee ness resistance The preceding and other runs indicate thatthe preferred molecular weight of the ethyl acrylateN-methylolacrylamide copolymer is at about 1 million. Higher molecularweight copolymers produce improved bonded fabrics but the improvementsare generally small.

Examples 18 to 22 -In these examples, the procedure of Example A isrepeated. Fibrous webs are formed by crosslaying polyester fibers, 1.5denier and 1.5 inches in length and submerging the webs in a bathprepared as in Example A. In these examples, however, the emulsioncopolymer is prepared by emulsion copolymerization of 3.5 parts N-methylolacrylamide and the amount of ethyl acrylate and itaconic acidindicated in Table 6 as Examples 18 to 22. Properties of the resultingfibrous webs are shown in Table 6.

These examples show the increase in stiffness in the bonded fabric withincreased amount of itaconic acid in the bonding copolymer. It can beseen from these examples that any desired stiffness can easily beincorporated into a bonded non-woven fabric by controlling theproportion of itaconic acid in the emulsion copolymer.

TABLE 6 Properties of bonded fabrics IA, EA, Resili- Stifi- Solventpercent percent ence ness resistance Example 23 The procedure of Example3 is repeated except that emulsion copolymers are used of the followingcompositions:

(a) 48% of ethyl acrylate, 48% of butyl acrylate, 3.5% ofN-methylolacrylamide, and 0.5% of itaconic acid,

(b) 25% methyl acrylate, 71% butyl acrylate, 3% N methylolmethacrylamideand 1.0% methacrylic acid, and

(c) 75% ehtyl acrylate, 22% 2-ethylhexyl acrylate, and

3.0% of N-methylolacrylamide.

Example 24 The procedures of Example 23 (a), (b), and (c) are repeatedexcept that the amount of the polyethylene glycol is raised to 4%, basedon the weight of the copolymer.

I claim:

1. A composition comprising (1) a water-insoluble emulsion copolymerconsisting of 3 to 4.5% by Weight of an N-methylolamide selected fromN-methylolac'rylamide or N-methylolmethacrylamide, and, for the balanceto make percent, at least one ester of acrylic acid and a C to C-alkanol, and 0.5 to 5% by weight, based on the copolymer weight, of anunsaturated aliphatic carboxylic acid having 3 to 6 carbon atoms,selected from itaconic acid, acrylic acid, methacrylic acid orcit'r'aconic acid and (2) about 0.5 to 10% by weight, based 'on theweight of the copolymer, of a polyalkylene glycol of the formula:

HO-(RO) --H wherein R is an alkylene group of 2 to '6 carbon atoms and nis a number having an average value of 4 to 50. 2. The composition ofclaim 1 in which the polyalkylene glycol is characterized by a molecularweight of 194 to 3. The composition of claim 1 in which the polyalkyleneglycol is a polyethylene glycol characterized by a molecular weight of300 to 2000.

4. The composition of claim 1 in which the copolymer comprises 3 to 4.5%by weight of N-methylolacrylamide, and 0.25 to 1% by weight of theunsaturated acid selected from itaconic acid, acrylic acid, methacrylicacid or citraconic acid and 2 to 5% by weight of the polyalkyleneglycol.

5. The composition of claim 4 in which the acid is itaconic acid.

6. A composition in accordance with claim 1 which also comprises up to20% by weight, based on the weight of the copolymer, of an aminoplast ora polyepoxide.

7. A composition comprising an aqueous dispersion of (1) awater-insoluble emulsion copolymer consisting of 3 to 4.5% by weight ofan N-methylolamide selected from N-methylolacrylamide orN-methylolmethacrylamide, and, for the balance to make 100 percent, atleast one ester of acrylic acid or methacrylic acid and a C to C-alkanol, and 0.5 to 5% by weight, based on the copolymer weight, of anunsaturated aliphatic carboxylic acid having 3 to 6 carbon atoms,selected from itaconic acid, acrylic acid, methacrylic acid orcitraconic acid and (2) about 0.5 to 10% by weight, based on the weightof the copolymer, of a polyalkylene glycol of the formula wherein R isan alkylene group of 2 to 6 carbon atoms and n is a number having anaverage value of 4 to 50.

8. The composition of claim 7 in which the copolymer comprises 3 to 4.5%by weight of N-methylolacrylamide, and 0.25 to 1% by weight of theunsaturated acid selected from itaconic acid, acrylic acid, methacrylicacid or citraconic acid and 2 to 5% by weight of the polyalkyleneglycol.

9. A composition in accordance with claim 7 which also comprises up to20% by weight, based on the weight of the copolymer, of an aminoplast ora polyepoxide.

References Cited UNITED STATES PATENTS 2,954,358 8/1960 Hurwitz260--29.6 MB 3,101,273 8/ 1963 Wagner et a1. 260--29.6 TA 3,157,56211/1964 Kine et a1 260-29.6 TA 3,231,533 1/1966 Garrett et al 260-296 TA3,300,431 1/1967 Ueno et al. 260-296 MB 3,445,403 5/ 1969 Tucker et al.26023 LUCTLLE M. PHYNES, Primary Examiner US. Cl. X.R.

260--29.6 NR, 29.6 RB, 29.6 RW, 29.6 TA, 29.6 MB, 78.5 BB, 80.73

